1. Field of the Invention
The present invention relates to a working machine, such as a demolition machine, equipped with a base machine and a working attachment to be attached to the base machine.
2. Description of the Background Art
There has been known a demolition machine equipped with an ultra-long attachment for use in demolishing e.g. high-rise buildings.
As shown in FIG. 11, the demolition machine is provided with a base machine 3, and a working attachment 4 to be attached to a front part of the base machine 3. The base machine 3 is provided with a crawler-type lower traveling body 1, and an upper rotating body 2 mounted on the lower traveling body 1 to turn around a vertical axis.
The working attachment 4 includes a base-end boom (hereinafter, simply called as a boom) 5 which is mounted on the base machine 3 (upper rotating body 2) to move up and down, a short-sized lead-end boom (hereinafter, called as an internal boom) 6 which is mounted on a lead end of the boom 5 to be pivotally movable about a horizontal axis for the purpose of expanding a working range, an arm 7 which is mounted on a lead end of the internal boom 6 to be pivotally movable about a horizontal axis, and a working device 8 (corresponding to a crusher called a nibbler in the example shown in FIG. 11) which is mounted on a lead end of the arm 7.
The boom 5 includes a main boom 5a which is provided on the lower side, and a front boom 5b which is provided on the upper side and which is detachably attached to the main boom 5a. The demolition machine is disassembled into a portion including the base machine 3 and the main boom 5a, and a portion of the working attachment 4 excluding the main boom 5a at the time of transport.
The front boom 5b generally has multi-stage boom members which are detachably attachable to each other. However, FIG. 11 shows the front boom 5b comprised of a single boom member to simplify the illustration.
Further, the demolition machine has plural cylinders (hydraulic cylinders) for moving the working attachment 4. Specifically, the demolition machine is provided with a boom cylinder 9 for moving the boom 5 (entirety of the working attachment 4) up and down, an internal boom cylinder 10 for moving the internal boom 6, an arm cylinder 11 for moving the arm 7, and a working device cylinder 12 for moving the working device 8.
The internal boom cylinder 10 is disposed between the boom 5 (front boom 5b) and the internal boom 6 at an inner position of the working attachment 4 when the working attachment 4 is folded. Similarly, the arm cylinder 11 is disposed between the internal boom 6 and the arm 7 at an inner position of the working attachment 4 when the working attachment 4 is folded.
The above arrangement is disclosed in Japanese Unexamined Patent Publication No. 2007-203221.
In the case where the demolition machine equipped with the ultra-long attachment having the above arrangement is disassembled, as shown by the solid line in FIG. 11, the working attachment 4 is placed on the ground in a triple-folded state, with the boom 5 being located on the upper side, and the arm 7 being located on the lower side with respect to the internal boom 6. In this state, the demolition machine is disassembled into the portion including the base machine 3 and the main boom 5a, and the portion of the working attachment 4 excluding the main boom 5a for transport, as described above.
Further, similarly to the disassembling operation as described above, assembling of the demolition machine after the transport is performed in a state that the portion of the triple-folded working attachment 4 (portion excluding the main boom 5a) is placed on the ground, with the boom 5 being located on the upper side, and the arm 7 being located on the lower side with respect to the internal boom 6.
In the demolition machine having the above arrangement, since the internal boom cylinder 10 and the arm cylinder 11 are disposed on the same position in the width direction of the working attachment 4, when the working attachment 4 is viewed from above in the folded posture indicated by the solid line in FIG. 11, it is necessary to secure a certain space between the cylinders 10 and 11 to keep the cylinders 10 and 11 from contacting with each other.
As a result, the heightwise space for the cylinders 10 and 11 is increased.
As shown in FIG. 12, attachment points of the boom 5 and the arm 7 with respect to the internal boom 6 are respectively indicated by the reference numerals X1 and X2, and attachment points (points of application of cylinder thrust force) of the internal boom cylinder 10 and the arm cylinder 11 with respect to the internal boom 6 are respectively indicated by the reference numerals Y1 and Y2. In this case, since the forces for moving the internal boom 6 and the arm 7 are proportional to the distance α1 (hereinafter, called as the moment length α1) between X1 and Y1, and the distance α2 (hereinafter, called as the moment length α2) between X2 and Y2, predetermined moment lengths α1 and α2 are required to secure intended application forces.
Consequently, since the distance (required length for the internal boom 6) between the boom 5 and the arm 7 in a folded posture is increased, the height (lead-end height H1 and overall height H2) of the working attachment 4 relative to the ground is increased.
Thus, in the demolition machine shown in FIGS. 11 and 12, disassembling and assembling operations are performed at a high position, and it is difficult or impossible to sufficiently secure enhanced safety and operability.
Further, since the overall height of the working attachment 4 at the time of transport is increased, it is impossible to transport the working attachment 4 by a truck even if the working attachment 4 meets the weight regulations, and it is necessary to transport the working attachment 4 by a low-floor trailer. Thus, the transport cost of the demolition machine is increased.